Methylmercury occurs as a contaminant of seafood and freshwater fish worldwide. Tragic pollution episodes have demonstrated that the fetal brain is particularly susceptible to methylmercury toxicity;the adverse effects on the nervous system appear to be irreversible and are much more widespread and serious in children than in adults, especially when exposures have occurred prenatally. This application builds upon the extensive data already collected on a cohort of 1,022 children born in 1986-1987. Detailed information was collected at the time of birth and during the course of follow-up at ages 7 and 14 years. Our previous research efforts have emphasized impacts during childhood and adolescence caused by developmental exposures to methylmercury as a possible paradigm for developmental neurotoxicant effects. The intention is now to complete the follow-up by examining the cohort members as young adults to determine the possible persistence of mercury-associated deficits in neuropsychological and cardiovascular functions, and the impact on educational achievements and overall health. The specific aims of this project are therefore to determine if methylmercury-associated cognitive deficits affect educational achievements, including high- school diploma and college (bachelor) studies;to examine cohort members at age 21 years to determine cardiovascular functions that may be affected by methylmercury exposure;to carry out analysis for PCBs in banked umbilical cord blood from cohort members, and to determine selenium intake from analysis of blood samples;and to assess genotypes for relevant genes that may affect methylmercury toxicokinetics or defense mechanisms against peroxidation processes that may be initiated by methylmercury exposure.